Epigenetic Controls in hESC Dopaminergic Fate

描述（由申请人提供）：干细胞，包括胚胎干细胞和体细胞干细胞，在人类疾病的组织和功能恢复方面具有巨大的潜力。然而，我们缺乏对干细胞向特定表型分化的精确过程的理解，甚至缺乏对特定疾病具有最大治疗潜力的干细胞的最佳来源，这反映了我们对基本干细胞生物学知识的差距，并且仍然是有效临床转化的障碍。对“干性”基因的研究表明，基因表达本身不足以确保或定义可塑性或谱系规范。我们假设(a)通过表观遗传过程表征人类干细胞将为未分化的人类胚胎干细胞（hESCs）的多能性及其分化级联提供潜在的机制

DESCRIPTION (provided by applicant): Stem cells, both embryonic and somatic, hold great potential for tissue and function restoration in human diseases. However, our lack of understanding regarding the precise process by which stem cells differentiate towards a particular phenotype or even the optimal source of stem cells with the greatest therapeutic potential for a particular disease reflects gaps in our knowledge of the fundamental stem cell biology and remains an obstacle to effective clinical translation. The search for "stemness" genes has suggested that gene expression alone is not sufficient to insure or define either plasticity or lineage specification. We hypothesize (a) that characterization of human stem cells by epigenetic processes will provide an underlying mechanism for the pluripotency of undifferentiated human embryonic stem cells (hESCs) and the differentiation cascades of their progeny; (b) that epigenetic marks, as established across development by the dynamics of chromatin remodeling, can be used to define potency, plasticity, and lineage-commitment along the continuum of human stem cell development; and (c) that such marks can be used to judge the therapeutic potential of a cell. The goal of this research proposal is to study the epigenetic controls of the hESC (NIH registry code: WA01, WA07, and WA09) as it differentiates towards a human neural stem cell (hNSC) and then a dopaminergic (DA) phenotype. Having established in our lab strategies for differentiating pluripotent hESCs towards becoming multipotent hNSCs and then towards DA neurons under defined culture conditions, and having generated a number of hNSC lines which can also be directed towards a DA phenotype, I will characterize the differentiation process by examining the progression of chromatin states and identify epigenetic landmarks. The profile of epigenetic marks in hESC differentiation will be compared to that of the CNS-derived hNSCs and their differentiated DA neurons. The identified epigenetic landmarks will be used to define and compare the plasticity and potential of human stem cells. These characteristics will be further affirmed by using an in vivo bioassay (a mouse model of DA dysfunction in the aged brain) to test and predict the therapeutic potential of a given stem cell state. The mentorship I will receive in the Snyder lab while pursuing the goals of this proposal will be significant for developing my future career as an independent human stem cell investigator.